In a mobile communications system, when a mobile station in a connected state moves from one cell to another cell, to prevent communication from being interrupted, a communications network control system usually starts a handover process to ensure service transmission of the mobile station. A handover technology used in a Wideband Code Division Multiple Access (WCDMA) system mainly includes an intra-system hard handover, an inter-system hard handover, a soft handover, and a softer handover.
For a soft handover, a mobile station is located in an overlapped part covered by two sectors of different base stations. In a downlink direction from the base stations to the mobile station, the mobile station simultaneously communicates with the two base stations by using air interface channels from the two base stations, and receives, by using a Rake receiver and in a manner of maximum ratio combining, signals transmitted by the two air interface channels. In an uplink direction from the mobile station to the two base stations, the two base stations receive encoded signals sent by the mobile station, decode the encoded signals, and send decoding results and cyclic redundancy check (CRC) check results to a radio network controller (RNC); and the RNC performs selective combining according to the CRC check results, and sends a result of the selective combining to a core network, to perform a subsequent communication process.
However, as the RNC performs selective combining according to the CRC check results, a macro diversity gain of the soft handover cannot be fully used, so that a maximum gain of a signal cannot be obtained.